/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/

This software is provided 'as-is', without any express or implied warranty.
In no event will the authors be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it freely,
subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/

#include "btSimpleDynamicsWorld.h"
#include "btCollisionDispatcher.h"
#include "btSimpleBroadphase.h"
#include "btCollisionShape.h"
#include "btRigidBody.h"
#include "btSequentialImpulseConstraintSolver.h"
#include "btContactSolverInfo.h"


/*
  Make sure this dummy function never changes so that it
  can be used by probes that are checking whether the
  library is actually installed.
*/
extern "C"
{
    void btBulletDynamicsProbe ();
    void btBulletDynamicsProbe () {}
}




btSimpleDynamicsWorld::btSimpleDynamicsWorld(btDispatcher* dispatcher,btBroadphaseInterface* pairCache,btConstraintSolver* constraintSolver,btCollisionConfiguration* collisionConfiguration)
:btDynamicsWorld(dispatcher,pairCache,collisionConfiguration),
m_constraintSolver(constraintSolver),
m_ownsConstraintSolver(false),
m_gravity(0,0,-10)
{

}


btSimpleDynamicsWorld::~btSimpleDynamicsWorld()
{
    if (m_ownsConstraintSolver)
        btAlignedFree( m_constraintSolver);
}

int        btSimpleDynamicsWorld::stepSimulation( btScalar timeStep,int maxSubSteps, btScalar fixedTimeStep)
{
    (void)fixedTimeStep;
    (void)maxSubSteps;


    ///apply gravity, predict motion
    predictUnconstraintMotion(timeStep);

    btDispatcherInfo&    dispatchInfo = getDispatchInfo();
    dispatchInfo.m_timeStep = timeStep;
    dispatchInfo.m_stepCount = 0;
    dispatchInfo.m_debugDraw = getDebugDrawer();

    ///perform collision detection
    performDiscreteCollisionDetection();

    ///solve contact constraints
    int numManifolds = m_dispatcher1->getNumManifolds();
    if (numManifolds)
    {
        btPersistentManifold** manifoldPtr = ((btCollisionDispatcher*)m_dispatcher1)->getInternalManifoldPointer();

        btContactSolverInfo infoGlobal;
        infoGlobal.m_timeStep = timeStep;
        m_constraintSolver->prepareSolve(0,numManifolds);
        m_constraintSolver->solveGroup(0,0,manifoldPtr, numManifolds,0,0,infoGlobal,m_debugDrawer, m_stackAlloc,m_dispatcher1);
        m_constraintSolver->allSolved(infoGlobal,m_debugDrawer, m_stackAlloc);
    }

    ///integrate transforms
    integrateTransforms(timeStep);

    updateAabbs();

    synchronizeMotionStates();

    clearForces();

    return 1;

}

void    btSimpleDynamicsWorld::clearForces()
{
    ///@todo: iterate over awake simulation islands!
    for ( int i=0;i<m_collisionObjects.size();i++)
    {
        btCollisionObject* colObj = m_collisionObjects[i];

        btRigidBody* body = btRigidBody::upcast(colObj);
        if (body)
        {
            body->clearForces();
        }
    }
}


void    btSimpleDynamicsWorld::setGravity(const btVector3& gravity)
{
    m_gravity = gravity;
    for ( int i=0;i<m_collisionObjects.size();i++)
    {
        btCollisionObject* colObj = m_collisionObjects[i];
        btRigidBody* body = btRigidBody::upcast(colObj);
        if (body)
        {
            body->setGravity(gravity);
        }
    }
}

btVector3 btSimpleDynamicsWorld::getGravity () const
{
    return m_gravity;
}

void    btSimpleDynamicsWorld::removeRigidBody(btRigidBody* body)
{
    removeCollisionObject(body);
}

void    btSimpleDynamicsWorld::addRigidBody(btRigidBody* body)
{
    body->setGravity(m_gravity);

    if (body->getCollisionShape())
    {
        addCollisionObject(body);
    }
}

void    btSimpleDynamicsWorld::updateAabbs()
{
    btTransform predictedTrans;
    for ( int i=0;i<m_collisionObjects.size();i++)
    {
        btCollisionObject* colObj = m_collisionObjects[i];
        btRigidBody* body = btRigidBody::upcast(colObj);
        if (body)
        {
            if (body->isActive() && (!body->isStaticObject()))
            {
                btVector3 minAabb,maxAabb;
                colObj->getCollisionShape()->getAabb(colObj->getWorldTransform(), minAabb,maxAabb);
                btBroadphaseInterface* bp = getBroadphase();
                bp->setAabb(body->getBroadphaseHandle(),minAabb,maxAabb, m_dispatcher1);
            }
        }
    }
}

void    btSimpleDynamicsWorld::integrateTransforms(btScalar timeStep)
{
    btTransform predictedTrans;
    for ( int i=0;i<m_collisionObjects.size();i++)
    {
        btCollisionObject* colObj = m_collisionObjects[i];
        btRigidBody* body = btRigidBody::upcast(colObj);
        if (body)
        {
            if (body->isActive() && (!body->isStaticObject()))
            {
                body->predictIntegratedTransform(timeStep, predictedTrans);
                body->proceedToTransform( predictedTrans);
            }
        }
    }
}



void    btSimpleDynamicsWorld::predictUnconstraintMotion(btScalar timeStep)
{
    for ( int i=0;i<m_collisionObjects.size();i++)
    {
        btCollisionObject* colObj = m_collisionObjects[i];
        btRigidBody* body = btRigidBody::upcast(colObj);
        if (body)
        {
            if (!body->isStaticObject())
            {
                if (body->isActive())
                {
                    body->applyGravity();
                    body->integrateVelocities( timeStep);
                    body->applyDamping(timeStep);
                    body->predictIntegratedTransform(timeStep,body->getInterpolationWorldTransform());
                }
            }
        }
    }
}


void    btSimpleDynamicsWorld::synchronizeMotionStates()
{
    ///@todo: iterate over awake simulation islands!
    for ( int i=0;i<m_collisionObjects.size();i++)
    {
        btCollisionObject* colObj = m_collisionObjects[i];
        btRigidBody* body = btRigidBody::upcast(colObj);
        if (body && body->getMotionState())
        {
            if (body->getActivationState() != ISLAND_SLEEPING)
            {
                body->getMotionState()->setWorldTransform(body->getWorldTransform());
            }
        }
    }

}


void    btSimpleDynamicsWorld::setConstraintSolver(btConstraintSolver* solver)
{
    if (m_ownsConstraintSolver)
    {
        btAlignedFree(m_constraintSolver);
    }
    m_ownsConstraintSolver = false;
    m_constraintSolver = solver;
}

btConstraintSolver* btSimpleDynamicsWorld::getConstraintSolver()
{
    return m_constraintSolver;
}
